Process for the preparation of dyeable acrylonitrile polymer fibers and compositions thereof



United States Patent PROCESS FOR THE PREPARATION OF DYEABLE ACRYLONITRELE POLYMER FIBERS AND COM- POSITIONS THEREOF Horace M. Robinson, Cary, N.C., assignor to Monsanto Company, a corporation of Delaware No Drawing. Fiied Feb. 14, 1963, Ser. No. 258,631 11 Claims. (Cl. 8-400) This invention relates to improved acrylonitrile polymer compositions. More particularly, the invention relates to improving the basic dye acceptance of shaped articles comprising acrylonitrile polymers by adding certain anionic sulfonate compounds to' the fiber in the gel state.

Acrylonitrile polymer compositions, particularly fiberforming compositions, possess a number of characteristics which render them of substantial value for a variety of textile and other purposes. However, it is also Well known that such compositions are difficult to dye With basic dyes due'to the hydrophobic nature of acrylonitrile fibers, filaments and other shaped articles. A large number of basic dyes have recently been developed with good fastness properties. This has rendered of prime importance attempts to improve the basic'dyeabilityof acrylonitrile polymer compositions. Various means have been developed to bring about this improvement. Acrylonitrile monomers have been polymerized with small amounts of a copolymerizable monomer such as an unsaturated sulfonate. Blends of acrylonitrile polymers with polymers having basic dyeability have been attempted. The use of pressure dyeing techniques at temperatures above the atmospheric boiling point of the polymeric mixture, low temperature dyeing processes and various special dyeing assistants have also partly alleviated this problem but are too limited in scope to be generally useful. A simpler means of increasing basic dye acceptance of acrylonitrile polymers is highly desirable. Such means should enable satisfactory level dyeing to the desired shades using conventional dyes and methods. It should produce a modified fiber that is susceptible to all types of basic dyes without otherwise changing the desired physical characteristics.

Accordingly, it is an object of this invention to provide acrylonitrile polymer fibers and filaments having good basic dye acceptance. 4

An additional object of the invention is to increase the basic dye receptivity of acrylonitrile polymer fibers and filaments by the incorportion therewith of alkyl aryl sulfonates.

Another object 'is to provide a process for the preparation of acrylonitrile polymer filbers and filaments containing basic dye receptive agents.

Other objects and ameliorations of the invention will become apparent from a consideration of the description of the invention as set forth herein.

The objectives of the invention are generally accomplished by contacting the acrylonitrile fiber in the gel state with an alkyl aryl sulfonate of the general formula wherein X represents a monovalent salt forming ingredient, for example, an alkali metal such as sodium or potassium, an amine such as methylamine, ethylamine, isopropyl amine, n-propylamine, or isobutylamine, or any other suitable salt forming component, R represents an alkyl radical containing from 4 to 12 carbon atoms and Ar represents an aromatic hydrocarbon radical containing 6 to 12 carbon atoms, the sulfonate preferably used in a treatment bath in the form of an aqueous solution containing from 0.1 percent to percent of the sulfonate salt, based on the Weight of the solution.

cannot act as co-polymerizable monomers.

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It has been found that the alkyl aryl sulfonates of this invention may be added to solution spun acrylonitrile fibers and filaments after extrusion, coagulation and orientation while the fibers are still in the gel state. The use of the term gel state refers to the condition of 'the fiber after extrusion and during coagulation, washing and orientation of the molecules by stretching and before the fiber is collapsed by drying to its final density and area ratio. During this gel state the fiber has a bulk density of .4 to .6 gm./cc., measured on a freeze dried sample.

to the density of the polymer prior to extrusion. the sulfonatesemployed in the practice of this invention contain no vinyl or other unsaturation components, they Furthermore, they cannot be satisfactorily applied as an additive after the fiber is collapsed and dried since subsequent scouring and other textile processing operations will remove most of the sulfonate which is deposited on :the surface rather than throughout the fiber; But, if

the sulfonate is added to the fiber in the gel, state, preferably by means of a separate treatment bath, it is occluded into the fiber, forming anionic dye sites in situ, and also keeping other dye sites which may be present in the fiber open and receptive to dyes. Thus, these sulfonates may be referred to'a's anionic gelstate additives. .The fiber may then be collapsed, dried and subjected to further processing without the loss of the sulfonate.

The amount of alkyl aryl sulfonate which may be employed in the practice of this invention will of course vary with the concentration of sulfonate in solution and with the spinning conditions. In general, the sulfonates are used in the form of an aqueous solution containing from 0.1 to 5 percent sulfonate preferably 1 to 2 percent, based on the'weight of the solution. been determined that approximately 50'to 60 percent of the concentration of sulfonate in the solution will be absorbed by the gel fiber as it passes through the treatment bath. This means that the fiberin its final form after collapsing and any'further treatments that may be used will contain from about .05 to 3 percent alkyl aryl sulfonate, based on the weight of the fiber.

Suitable alkyl aryl sulfonates which may beused in the practice of the invention are those which correspond to the general formula 'wherein X represents a monovalent salt forming radical,

mentioned the alkali metal alkyl aryl sulfonates suchas sodium ethylbenzene sulfonate, sodium butylbenzene sulfonate, sodium 2 butyl naphthylene 6 sulfonate,

sodium 2 isopropylnaphthylene -6 sulfonate, sodium propylbenzene sulfonate, sodium isopropylbenzene sulfonate, sodium dodecylbenzene sulfonate, sodium 3-buty1 toluene 5 sulfonate, the corresponding potassium derivatives, and amine alkyl aryl sulfonates such as amine butylbenzene sulfonate, amine pentylbenzene sulfonate, amine hexylbenzene sulfonate, methylamine butylbenzene sulfonate, isopropylamine dodecylbenzene sulfonate, ethylamine hexylbenzene sulfonate, isobutylamine octylbenzene sulfonate, n-p'ropylamine decylbenzene sulfonate The acrylonitrile polymers of this invention include After collapsing the fiber has a density of from about 1.16 to 1.19 gm./cc. Which is roughly equivalent Since.

It has polyacrylonitrile and copolymers, terpolymers, interpolypolymers and blends of acrylonitrile with other polymerizable mono-olefinic materials, as well as blends of polyacrylonitrile and such polymerized mono-olefinic materials with small amounts of other polymeric materials, such as styrene. In general, a polymer made from a monomer mixture of which acrylonitrile is at least 70 percent by weight of the polymerizable content or a blend of polymers containing at least 70 percent of polymerized acrylonitrile is useful in the practice of the invention. Block and graft copolymers of the same general type are within the purvue of the invention.

For example, the polymer may be a copolymer of from 80 to 98 percent acrylonitrile and from 2 to 20 percent of another monomer containing the C=C linkage and copolymerizable with acrylonitrile. Suitable mono-olefinic monomers include acrylic, alpha-chloroacrylic and methacrylic acids; the methacrylates such as methyl methacrylate, ethyl methacrylte, butyl methacrylate, octyl methacrylate, methoxymethyl methacrylate, beta-chloroethyl methacrylate, and the corresponding esters of acrylic and alpha-chloroacrylic acids; vinyl chloride, vinyl fluoride, vinyl bromide, vinylidene chloride, l-chloro-lbromoethylene; methacrylonitrile; acrylamide and methacrylamide, alpha-chloroacrylamide or monoalkyl substitution products thereof; methyl vinyl ketone; vinyl carboxylates such as vinyl acetate, vinyl chloroacetate, vinyl propionate and N-vinylsuccinimide; methylene malonic esters; itaconic esters; N-vinylcarbazole; vinyl furane; alkyl vinyl ethers; vinyl sulfonic acid; ethylene alpha-, beta-dicarboxylic acids or their anhydridesor derivatives such as diethyl fumarate, diethyl maleate, diethyl citraconate, diethylmesaconate; styrene; vinyl naphthalene; acenaphthalene; vinyl-substituted tertiary heterocyclic amines, such as the vinylpyridines, for example, 2-vinylpyridine, 4-vinylpyridine, 5-methyl-2-vinylpyridine, etc., l-vinylimidazole and alkyl-substituted l-vinylimidazoles, such as 2-, 4-, or 5-methyl-l-vinylimidazole, and other C=C containing copolymerizable materials.

The polymer may be a ternary interpolymer, for example, products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers enumerated above. More specifically, a useful ternary polymer comprises acrylonitrile, methacrylonitrile, and 2- vinylpyridine. The ternary polymers may contain, for example, from 80 to 97 percent of acrylonitrile, from 1 to percent of a vinylpyridine or a l-vinylimidazole, and from 1 to 18 percent of another substance, such as methacrylonitrile or vinyl chloride.

The polymer may also be a blend of from 50 to 98 percent of polyacrylonitrile or of a polymer containing from 80 to 99 percent acrylonitrile and from 1 to 20 percent of at least one other C=C containing substance copolymerizable with acrylonitrile, with from 2 to 50 percent of a blending polymer of from 10 to 70 percent of acrylonitrile and from 30 to 90 percent of at least one other C=C containing polymerizable monomer. Preferably, when the polymeric material comprises a blend, it will be a blend of (1) a copolymer of 90 to 98 percent of acrylonitrile and from 2 to 10 percent of another mono-olefinic monomer such as vinyl acetate, with (2) a suificient amount of a copolymer of from 10 to 70 percent of acrylonitrile and from 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, such as vinylpyridine, methyl vinylpyridine or l-vinylimidazole, the two blending polymers being so as to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10 percent based on the weight of the blend. Other blend compositions such as blends of polyvinyl chloride or polyvinylidene chloride with the above described blends, the overall blending composition containing at least 70 percent polymerized acrylonitrile are also within the purview of the invention.

The polymers useful in the practice of the present invention may be prepared by any conventional polymerization procedure, such as mass polymerization methods, solution polymerization methods, or aqueous emulsion procedures. The preferred practice utilizes suspension polymerization wherein the polymer is prepared in finely divided form for immediate use in the fiber fabrication operations. The preferred suspension polymerization may utilize batch procedures wherein monomers are charged with an aqueous medium containing the necessary catalyst and dispersing agents. A more desirable method involves the semi-continuous procedure in which the polymerization reactor containing the aqueous medium is charged with the desired monomers gradually throughout the course of the reaction. Entirely continuous methods involving the gradual addition of monomers and the continuous withdrawal of polymer may also be employed.

The most effective polymers for the preparation of fibers are those of uniform physical and chemical properties and of relatively high molecular weight. The polymers should have molecular weights of at least about 10,000 and preferably between about 25,000 and 150,000.

In preparing the products of the present invention, conventional equipment ordinarily employed in the manufacture of artificial and synthetic fibers and filaments may be used and particularly the equipment which is usually emplayed in the manufacture of fibers and filaments from acrylonitrile polymers. The present invention is applicable to the usual methods for forming synthetic filaments and fibers, such as dry spinning and wet spinning. Any of the well known prior art solvents, coagulation baths and orientation and washing methods normally used in solution spinning may be used in the practice of the invention. Heat and light stabilizers, delusterants, plasti -cizers and other like modifying agents may be incorporated with the polymeric compositions disclosed herein Without departing from the scope of the invention and without detrimental effects from these gel state additives. Antistatic agents, lubricants and other additives which are either anionic or nonionic may be applied to the fiber in the gel state along with the sulfonates of this invention.

The process and composition of this invention is of distinct advantage over the prior art. There is no need to use inconvenient pressure dyeing conditions to achieve commercially acceptable dyeing properties. The involved step of the incorporation of dye receptive materials in the polymer during its preparation is eliminated. Basic dye acceptance of the alkyl aryl sulfonate containing acrylic fibers of the invention is at a sufficiently high level to make possible dyeing in deep shades with basic dyes. Color, heat stability, dye penetration and washfastness are also improved. Numerous other advantages of the present invention will be apparent to those skilled in the art.

The following examples are presented as a further disclosure and illustration of the improved products of this invention and are not intended as a limitation thereof. All parts, proportions and percentages are by weight unless otherwise indicated.

EXAMPLE I An acrylonitrile polymer comprising percent acrylonitrile and 5 percent vinyl acetate was wet spun by standard procedures of the .prior art into a coagulation bath containing dimethylacetamide and Water, and the gel fiber then passed through a treatment bath containing a 1 percent aqueous solution of the isopropylamine salt of dodecylbenzene sulfonate. Results of basic dye acceptance (BDA) Were obtained by dyeing scoured fiber sample with 20 percent Sevron Blue 2G (Cl. Basic Blue 22) in a 40:1 bath ratio at C. for two hours. Percent BDA was calculated from the dye remaining in the bath using a standard formula based on optical density. The average percent BDA was calculated on the basis of the weight of the fiber.

EXAMPLE II In this example the acrylonitrile polymer composition of Example I was treated in the gel state with a solution bath containing a 2 percent aqueous solution of sodium dodecylbenzene sulfonate, sodium 2-isopropyl naphthalene-6-sulfonate, sodium 2-butyl naphthalene-6-sulfonate, and a control run as in Example I. Results of basic dye acceptance were obtained as in Example I by dyeing scoured fiber samples with 20 percent Sevron Blue 26 (CI. Basic Blue 22) in a 40:1 bath ratio at 100 C. for 2. hours. Percent BDA was calculated from the dye remaining in the bath using a standard formula based on optical density. The average percent BDA was calcu- When the above examples are repeated with other alkyl aryl sulfonates similar results are obtained. The increase in basic dye acceptance over the control is at least about 70 percent or greater in all instances and in many cases is over 100 percent.

The foregoing detailed description has been given for clearness of understanding only and unnecessary limitations are not to be construed therefrom. The invention is not to be limited to the exact details shown and described, since obvious modifications will occur to those skilled in the art and any departure from the description herein that conforms to the present invention is intended to be included within the scope of the claims.

What is claimed is:

1. A new composition of matter comprising an acrylonitrile polymer fiber and from .05 to 3 percent by weight of an alkyl aryl sulfonate selected from the group consisting of sodium dodecyl-benzene sulfonate, sodium 2-isopropylnaphthalene-6-sulfonate, sodium Z-butylnaphthalene-6-sulfonate and the isopropylamine salt of dodecylbenzene sulfonate.

2. The composition of claim 1 wherein the acrylonitrile polymer fiber consists of polyacrylonitrile.

3. The composition of claim 1 wherein the acrylonitrile polymer fiber consists of a copolymer of at least 80 percent acrylonitrile and up to 20 percent of a copolymerizable mono-olefinic monomer 4. The composition of claim 1 wherein the acrylonitrile polymer fiber consists of a blend of 80 to 99 percent of (A) a copolymer containing 80 to 98, percent of acrylonitrile and 2 to 20 percent of another rnono-olefinic monomer and 1 to 20 percent of (B) a copolymer containing 10 to percent of acrylonitrile and 30 to 90 percent of a vinyl-substituted tertiary heterocyclic amine, said blend having an overall vinyl-substituted tertiary amine content of 2 to 10 percent, based on the weight of the blend.

5. A new composition of matter comprising .an acrylonitrile polymer fiber consisting of a copolymer containing 95 percent acrylonitrile and 5 percent vinyl acetate, said acrylonitrile polymer fiber containing 1 percent by weight of sodium dodecylbenzene sulfonate.

6. A process for the preparation of dyeable acrylonitrile polymer fibers comprising contacting the fiber with from 0.1 to 5 percent, based on the weight of the solution, of a solution of an alkyl aryl sulfonate selected from the group consisting of sodium dodecylbenzene sulfonate, sodium 2-isopropylnaphthalene-6-sulfonate, sodium 2-butylnaphthalene-6-sulfonate and the isopropylamine salt of dodecylbenzene sulfonate, and drying the resultant alkyl aryl sulfonate containing acrylonitrile fiber.

7. The process of claim 6 wherein the acrylonitrile polymer fiber consists of polyacrylonitrile.

8. The process of claim 6 wherein the acrylonitrile polymer fiber consists of a copolymer of at least percent acrylonitrile and up to 20 percent of a copolymerizable 'rnono-olefinic monomer.

9. The process of claim 6 wherein the acrylonitrile polymer fiber consists of a blend of 80 to 99 percent of (A) a copolymer containing 80 to 98 percent of acrylonitrile and 2 to 20 percent of another mono-olefinic rnonomer and 1 to 20 percent of (B) a copolymer containing 10 to 70 percent of acrylonitrile and 30 to percent of a vinyl-substituted tertiary hcterocyclic amine, said blend having an overall vinyl-substituted tertiary amine content of 2 to 10 percent, based on the weight of the blend.

10. A process for the preparation of dyeable acrylonitrile polymer fibers comprising contacting the fiber in the gel state with from 0.1 to 5 percent based on the weight of the solution, of a solution of an alkyl aryl sulfonate selected from the group consisting of sodium dodecylbenzene sulfonate, sodium Z-isopropylnaphthalene 6-sulfonate, sodium 2-butylnaphthalene-6-sulfonate and the isopropylamine salt of dodecylbenzene sulfonate, and drying the resultant alkyl aryl sulfonate containing acrylonitrile polymer fiber to produce a dyeable fiber having a density of at least 1.14.

11. A process for the preparation of a dyeable acrylonitrile copolymer fiber consisting of a copolymer of percent acrylonitrile and 5 percent vinyl acetate, comprising contacting said fiber in the gel state with 2 percent based on the weight of the solution, of a solution of sodium dodecylbenzene sulfonate and drying the resultant sodium dodecylbenzene sulfonate containing acrylonitrile copolymer fiber to produce a dyeable fiber having a density of at least 1.14.

References Cited by the Examiner UNITED STATES PATENTS 2,484,430 10/ 1949 Sprague et al. 2,759,975 8/1956 Chiddix et al. 3,097,054 7/1963 Routson et al. 3,108,011 10/ 1963 Frotsc-her.

NORMAN G. TORCHIN, Primary Examiner. J. I. HERBERT, Assistant Examiner. 

1. A NEW COMPOSITION OF MATTER COMPRISING AN ACRYLONITRILE POLYMER FIBER AND FROM .05 TO 3 PERCENT BY WEIGHT OF AN ALKYL ARYL SULFONATE SELECTED FROM THE GROUP CONSISTING OF SODIUM DODECYBENZENE SULFONATE, SODIUM 2-ISOPROPYLNAPHTHALENE-6-SULFONATE, SODIUM 2-BUTYLNAPHTHALENE-6-SULFONATE AND THE ISOPROPYLAMINE SALT OF DODECYLBENZENE SULFONATE.
 6. A PROCESS FOR THE PREPARATION OF DYEABLE ACRYLONITRILE POLYMER FIBERS COMPRISING CONTACTING THE FIBER WITH FROM 0.1 TO 5 PERCENT, BASED ON THE WEIGHT OF THE SOLUTION, OF A SOLUTION OF AN ALKYL ARYL SULFONATE SELECTED FROM THE GROUP CONSISTING OF SODIUM DODECYLBENZENE SULFONATE, SODIUM 2-ISOPROPYLNAPTHALENE-6-SULFONATE, SODIUM 2-BUTYLNAPTHALENE-6-SULFONATE AND THE ISOPROPYLAMINE SALT OF DODECYLBENZENE SULFONATE, AND DRYING THE RESULTANT ALKYL ARYL SULFONATE CONTAINING ACRYLONITRILE FIBER. 